Interpretive Summary: Sugarbeet root maggot is a serious pest of sugarbeet in much of North America. Yield reductions due to root maggot feeding may be caused by stand loss early in the season but, damage occurs primarily from feeding throughout the growing season. If the root maggot were to develop resistance to the few insecticides currently used or these insecticides became unavailable because of environmental concerns, sugarbeet production in some areas would be threatened. Host plant resistance to the root maggot would provide an alternative control method and has some advantages even if the insecticides continue to be effective. Currently, selection for root maggot resistance is dependent upon natural infestations at sites where root maggot populations are usually high. Two resistant germplasms have been developed and are available for use by commercial sugarbeet breeders and two globe-shaped red beet lines appear to have resistance.

Technical Abstract:
Sugarbeet root maggot (Tetanops myopaeformis) is a serious pest of sugarbeet (Beta vulgaris) in much of North America. Yield reductions due to root maggot feeding may be caused by stand loss early in the season but, damage occurs primarily from feeding throughout the growing season. If the root maggot were to develop resistance to the few insecticides currently used or these insecticides became unavailable because of environmental concerns, sugarbeet production in some areas would be threatened. Host plant resistance to the root maggot would provide an alternative control method and has some advantages even if the insecticides continue to be effective. Currently, selection for root maggot resistance is dependent upon natural infestations at sites where root maggot populations are usually high. A 0 = no damage to 9= severe damage rating scale has been developed to assess damage and evaluate lines in a breeding program. Two resistant germplasms have been developed and are available for use by commercial sugarbeet breeders and two globe-shaped red beet lines appear to have resistance. Immunity to sugarbeet root maggot feeding has not been found.